In a class, 11 girls jumped an average of 1.51 m for their standing broad jump in their fitness test. The boys in the same class jumped an average of 1.66 m in the same test. The total average of the whole class was 1.55 m. How many boys were there?
|
Girls |
Boys |
Children |
Number |
11 |
1 u |
1 u + 11 |
Value |
1.51 |
1.66 |
1.55 |
Total Value |
16.61 |
1.66 u |
1.55 u + 17.05 |
Total number of boys = 1 u
Total number of children = 1 u + 11
Total length that the girls jumped
= 11 x 1.51
= 16.61 m
Total length that the boys jumped
= 1 u x 1.66
= 1.66 u
Total length that the children jumped
= 1.55(1 u + 11)
= 1.55 u + 17.05
16.61 + 1.66 u = 1.55 u + 17.05
1.66 u - 1.55 u = 17.05 - 16.61
0.11 u = 0.44
1 u = 0.44 ÷ 0.11 = 4
Number of boys
= 1 u
= 4
Answer(s): 4